I've spent almost a year on the G1, and I'm not aware of any method to adjust its sensitivity. It's always just as broadly/coarsely over-sensitive no matter what. A slight tremor in the thumb and it will dump to the next item when you try to click. A slip of the thumb at the wrong moment can move you multiple widgets along (this is especially annoying with Google Reader, for example, but also in the web browser, or even in Gmail -- but to see what I mean for Google Reader, try to click on the "keep unread" checkbox for a large range of messages, where the messages have lots of links (a combined list of engadet and slashdot articles ought to do the trick) ... it's one of those things that's so obtuse that, in my experience, only has a 40-60% chance of success averaged out over multiple attempts on multiple articles -- try doing it with your finger, too).

I have used a BB Curve many times, but not as consistently and continuously as the G1 (my G1 has been my only pocketable device, carried with me almost constantly, since last October).

Getting the trackball to roll in the intended direction isn't a problem. Getting it to only roll as far as I want, and be sure it doesn't roll at all when I click, those are the problems. And those are what keep it from meeting my requirement for precision.

"No more stylus" _included_. That doesn't mean it can't be useful to have one. There are, for example, accessory styli you can get for the iPhone. I would similarly expect/want one for the N900. And I wish I could find a stylus that would work with the G1 (I'd probably only RARELY use it, but there are cases where I definitely wish I had one to use).